Why no payshap,but it's an option

What i don't understand is why they have the payshap option.Ive booked 4 rides so far and the driver that pitches doesn't have payshap, yet when you book the ride you clearly say payshap. It causes tassels with the driver. I usually do a cashed,but the amount may be under a 100. The atms don't have 20 rand notes. This means the driver can't draw the money and lands up phoning you.